Flow meter



Patented Jan. 29, 1935 4 66 I UNITED STATES PATENT OFFICE Application N0. 582,754

My invention relates to appliances for the the cap, 9, extend for some distance over the measuring of the flow of fluids. shell, '7, which divides the interior of 8 and 9 The objects of my invention are to produce an in each case into two chambers, one of which instrument of the character described of great is indicated by M and one by 7b; and there are sensitiveness, wide range in capacity and paralso annular chambers, 8a and 9a. Foraminous 5 ticularly to overcome the difliculties now present screens, 10, are provided between the chambers v in existing types of flow meters using Venturi 7a and 9a and 1b and 8a to prevent any foreign tubes and orifices and such like measuring conmatter passing through the instrument to intrivances that offer serious impedance'to the terfere with the mechanism thereof. I flow and which must be proportioned closely to The casing, A, in the present instance is a 10 the expected volume of flow in order to.be reatube having one side cut away as shown in Fig. sonably accurate. 2 and it is provided with'means such as the stuff- Another object of my invention is to produce ing boxes, A, for holding the transparent tube, an instrument of the character described where- 25, and the scales as hereinafter described in in the frictional resistance offered by the instrudetaiL. ment itself to the passage of the fluid being Inside of the shell, 7, or it may be madeinmeasured. will be at a minimum. tegral therewith if desired, is found a filler, 11,

A further object of 'my invention is to comand longitudinally of the center thereof on the bine the accuracy of the types mentioned with axis of the instrument is found a passageway, 12, the sensitiveness of a Pitot tube and without the which is the inverted frustum of a right cone.

disadvantages inherent in either type. The filler, 11, or its equivalent, should be made These and other objects of my invention in of a material having a very lowcoefiicient-of expart mentioned and in part obvious in the subpansion. For inert gases it can be made of neat joined description and claims constitute the pur- Portland cement moulded over a polished manpose of my invention. drel; for some instruments it can be ground glass A drawing accompanies and forms apart of this and for others of some of the steels having exspeciflcation and serves to illustrate an embodipansion coeflicicnts approximating zero within ment of my inventionfor the purpose of disclosordinary temperature ranges. ing the principles thereof, but it must be r'e- Within the cap, 8, is found a spider, 13, admembered that this is only one form of the many justably mounted in all horizontal directions as 30 forms that can be made to utilize the principles shown in Fig. 5 by threaded portions on the ends disclosed. of the spider and nuts, 14.

In the drawing, In the center of the spider, 13, is a tension Fig. 1 is an elevation of the complete instrustair, 15, provided with a nut, 16, which supment in this particular embodiment; ports and stresses a wire, 1'7. The other end of 35 Fig. 2 is a view of the same structure illu sthe wire, 1'1, is supported by the element, 18, trated in Fig. 1, viewed at a position at right which is here shown as a disc supported'on the angles thereto; structure, 19, and held fluid tight in place by the Fig. 3 is a longitudinal section of Fig. 2 on the cap, 20. Mounted on the wire, 17, is the stafi, 21, 40 line 33 of Fig. 2; which has a central bore that loosely accommo- 40 Fig. 4 is a section taken at the line 4-4 of dates the wire, 17, and mounted upon the lower Fig. 1; 1 end of the staff, 21, is a disc, 22, which can well Fig. 5 is a cross-section on the line 5-5 of be made curved as shown in Fig.3, and immedi- Fig. 3; and 5 ateLv below the disc, 22, and securely attached to Fig. 6 is a cross-section on the line 66 of the stall, 21, is a multi-bladed helical propeller, 45

Fig. 2; the arrows in each case indicating the 23, the purpose of which ishereinafter explained. direction of sight. The upper end of the stall, 21, serves as a pointer A shell, '7, is provided with caps, 8 and ,9, an to indicate the reading of the instrument on the an upstanding casing, A, is attached to the cap, scale, 24, which is on the outside of the trans- 9, for the purpose hereinafter disclosed. An inparent tube, 25. It will be noted that the scale, let, I, for the fluid to be measured is shown in 24, is provided with a duplicate scale,-24a, which the several views and an outlet, 0, indicates the is folded around the opposite side of transparent course of the fluid through the instrument. These tube, 25, with its indicia in registration with the two ducts will be exactly the same length and indicia on the scale, 24; the scale 24 is a flat rigid diameter. It will be noted that the cap, 8, 1d transparency such as glass having the scale en- 55 graved thereon and the scale 24a is of transparent material such as celluloid and is folded around the transparent tube 25 and has both edges firmly attached to the scale 24 so that the two scales together are movable up and down on the transparent tube 25. and to be set in the original calibration of the instrument in. a permanent relation to the tube.

The scale, 24a, is preferably made of celluloid or a similar opaque flexible material and is attached toscale 24 at its edges in any;well known or preferred manner. Scale 24, except the graduations thereon, is transparent and may be made of glass or any suitable synthetic transparent material.

The purpose of the scale, 24a, is to prevent misreading of the instrument due to the eye of the observer being at an improper angle. When the eye of the observer is at the proper angle only one set of'indicia will be seen and if at an improper angle a confusing blur of marks will indi-" cate the necessity of adjusting the eye at the proper level to read the instrument.

The scale members are graduated in units of area of the annular space between the'inner wall of the passageway 12 andthe disc 22 which increases disproportionately to the length of the scale, as shown in the drawing.

The staff, 21, the disc, 22, and the helical propeller, 23, should be made of material having a specific gravity slightly in excess of the fluid to be measured.

The inlet, I, and the outlet, 0, are the same size and it will be noted that all passages within the instrument with the exception about to be noted have a cross-sectional area considerably in excess of the area of the inlet or. outlet. The exception to this is the lower end of the passage, 12,

being the top of the frustum of the right cone when obstructed by the disc, 22. As shown in Fig. 3 the disc is shown in solid lines as at rest. It is shown in dotted lines at 22a at the position that it will occupy when the instrument is indicating a fluid flow to its maximum capacity. The staff, 21, is shown at 21a in dotted lines in the position that it will occupy when 22a serves to indicate the position of the disc, 22.

When fluid to be measured is admitted through the inlet, 1, it passes through the instrument and out of the outlet, 0, the disc, 22, will rise such a distance within the passageway, 12, that the area of the resulting annular clearance past the edge of the disc and between the disc and the walls of the passageway, 12, is proportional to the flow of the fluid;.thus when the disc is in position as shown at 22 in Fig. 3, the passageway, 12, will be entirely obstructed and the top. end of the staff, 21, will indicate zero on the scales, 24 and 24a. When it is at its maximum capacity it will indicate the amount of flow at the top of the scale whatever that may be. And at intermediate points the registration will correctly indicate the flow according to the scale previously computed. This scale is not a logarithmic scale nor is it a scale in arithmetical progression, but must be computed, which is a simple matter, for each cone. The arrangement of the chambers 8aand 7b, assures that no velocity of intake or efllux will affect measuring mechanism and the lower end of the frustro-conical measuring chamber is under the influence of pressure only, a part of this pressure will be transformed to velocity in passing from 7b to 7a where the velocity will practically disappear by being retransformed into pressure prior to going out through "0. The

volume passing a'given position of the disc 22 will therefore be the amount that will float the disc at that point. The weight of the disc being known, a constant is substituted for "p in the fundamental equations for the flow of fluids (see Engineers Handbook, first edition, Marks P 353-5) and the division lines on the scale should indicate the sum of uniform units of area of the misleading variables.

Where it is desirable to mix commercial gas and air in the proportions of say-6:l for furnace use the actual cubic feet of the air or gas is relatively unimportant, the gas being measured by a displacement meter and the air not requiring measurement at all except to get the correct proportion for eflicient combustion. Therefore, I will place one instrument on the gas line and another on a source of air under the correct pressure and regulate flows until the air instrument shows a flow of six units to one on the gas instrument and the result is accomplished without any calculations required of the user, if the instruments have been properly constructed.

The longer the cone for a given diameter of base and top the coarser the graduations of the scale and the more accurate the reading. This will not affect the accuracy of the meter since the resistance offered by the disc, 22, and the superposed weight of the staff,- 21, is a constant regardless of length of travel.

The purpose of the helical propeller, 23, is to impart a rotary motion .to the disc, 22, and the staff, 21, and it has been found that this or an equivalent damping means must be used to prevent such a rapid movement of the indicating end of the staff, 21, due perhaps to pulsations of flow if any are present, that the reading of the scales would be uncertain.

It will now be seen that the instrument possesses the following characteristics; since the staff, 21, and the disc, 22, with the attached parts can be made so that their weight submerged in the fluid to be measured is comparatively insigniflcant, that little if any appreciable impedance is offered to the flow 0f the fluid; it is believed to be the only instrument known that will measure the flow first of exceedingly small quantities of a gas and at the same time correctly indicate the amount of the flow of very large quantities of the same gas and that will not offer an impedance approximately equal to the square of the volume of the gas as the consumption or use through the instrument proceeds from zero to maximum. There is in fact no increase in the resistance to the flow between minimum and maximum and what resistance there is, beinga flxed quantity and known, can be taken care of in computing the scale and it will thus be seen that we have a flow meter'that fully fulfills the objects enumerated in the preamble to this specification, great sensitiveness, high accuracy, simplicity and without intricate parts to detract from reliability.

Of the many uses to which this-flow meter is adaptable, one may be cited as an outstanding example of its utility.

In aviation the proper consumption of fluid fuel of a motor is always definitely known when it is worfing at maximum efliciency. The operator or pilot, however, has no means of knowing whether the consumption of fuel with the motor in operation is greater or less than the desired amount. He must adjust the consumption purepeller and the screens should be made of such' material that they will not be affected by the fluid being measured should it have any efiect normally to corrode materials either with or without the presence of atmospheric oxygen.

Many difierent constructions are possible in which the principles herein disclosed may be applied to the use described. I therefore do not wish to be restricted in the application of my new invention except by the terms of the following claims.

What I. claim as new and desire to secure by Letters Patent, isv 1. In a flow meter, calibrated inlet and outlet means of equal capacity, a frustro-conical'passageway between said inlet and outlet means, a disc movable in said conical passageway under the influence of moving fluid, a hollow staff attached to said disc, a tension wire through said staif, means for centering and supporting said tension wire and a scale member adapted to indicate rates of flow as indicated by a point on said staff.

2. A flow meter of the character described defined in part as a flow measuring chamber that is a frustum of a cone, a cupped disc supported movably along the axis of said measuring chamher and movable axially therein under the influence of flowing fluid, a hollow stalI attached to said disc member, a tension wire adjustably supported axially of the frustro-conical measuring chamber, upon which the disc and stafi are slidable, the wire passing through the hollow of the stafi, and a propeller adapted to impart rotative motion to said disc under the influence of moving -fluid whereby the axial movement of said disc is damped without interfering with its free movement.

3. In a flow meter of the character described, a body member provided with inlet andoutlet means of the same capacity, a frustro-conical measuring chamber within said body member, velocity-pressure transformation chambers at both ends of said measuring chamber and communicating with said inlet and outlet means, respectively, a tension wire adjustably supported axially of the measuring chamber, a hollow staff upon said wire, a cupped disc mounted upon said staff perpendicular to the axis thereof, a damping means for said disc and means for visibly indicating the position of said disc with respect to the length of said measuring chamber.

4. In a flow meter for fluids, a body member for said meter enclosing a difiusion chamber at each end of said body, a irustro-conical flow measuring chamber positioned between the said diffusion chambers, a wire, adjustable means for supporting and carrying said wire axially of said measuring chamber, a hollow stafi movable upon said wire, a disc mounted upon the said staff, means for damping said disc, a scale means for reading the position of said disc in units of area of the annular space between the disc and the wall of the measuring chamber, said scale points being indicated by the end of the hollow staif opposite that upon which the disc is mounted.

FRED JONES. 

